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Pontal do Paraná, Brazil

Pires L.F.,State University of Ponta Grossa | Rosa J.A.,Instituto Agronomico Do Parana | Timm L.C.,Federal University of Pelotas
Acta Scientiarum - Agronomy | Year: 2011

Soil bulk density (ds) is traditionally used as an indicator of soil structure and soil compaction. The objective of this work was to compare ds values obtained through conventional methods like paraffin sealed clod (MTP) and volumetric ring (MAV), and nuclear methods like computerized tomography (MTC), gamma-ray attenuation (MAG) and neutron-gamma surface gauge (MSN). Soil samples were collected in areas under conventional tillage and no-tillage systems. Sixteen samples were collected in the soil surface layer for the analyses by the MAV, MTP, MTC, and MAG. For the MSN, sixteen readings were carried out throughout the experimental area. The highest ds values for the conventional tillage system were obtained for the MTP, MPC, and MAG, without significant differences. Also the statistic test indicates that the lowest ds values obtained for the MSN and MAV did not differ significantly. Regarding to the no-tillage system, only the MAV and MAG had been compared, whose ds values did differ significantly.

Cacao S.M.,Instituto Agronomico Do Parana
Genetics and molecular research : GMR | Year: 2012

Coffee quality is directly related to the harvest and post harvest conditions. Non-uniform maturation of coffee fruits, combined with inadequate harvest, negatively affects the final quality of the product. Pectin methylesterase (PME) plays an important role in fruit softening due to the hydrolysis of methylester groups in cell wall pectins. In order to characterize the changes occurring during coffee fruit maturation, the enzymatic activity of PME was measured during different stages of fruit ripening. PME activity progressively increased from the beginning of the ripening process to the cherry fruit stage. In silico analysis of expressed sequence tags of the Brazilian Coffee Genome Project database identified 5 isoforms of PME. We isolated and cloned a cDNA homolog of PME for further characterization. CaPME4 transcription was analyzed in pericarp, perisperm, and endosperm tissues during fruit development and ripening as well as in other plant tissues. Northern blot analysis revealed increased transcription of CaPME4 in the pericarp 300 days after flowering. Low levels of CaPME4 mRNAs were observed in the endosperm 270 days after flowering. Expression of CaPME4 transcripts was strong in the branches and lower in root and flower tissues. We showed that CaPME4 acts specifically during the later stages of fruit ripening and possibly contributes to the softening of coffee fruit, thus playing a significant role in pectin degradation in the fruit pericarp.

The least limiting water range (LLWR) is one of the best indicators of soil physical quality in intensive production systems. The objective of this study was to evaluate the physical quality of a Typic Haplorthox by the LLWR after three crop growing seasons and the first year of crop-livestock integration in Xambrê, northwestern Paraná, Brazil. The experiment was established in a randomized block design with three replications. Treatments consisted of four brachiaria heights before grazing (0.10; 0.20; 0.30, and 0.40 m) and a control treatment without grazing. The brachiaria (Brachiaria ruziziensis) was sown in March 2010 and cattle grazed on it continuously for 110 days (March-September). In October 2010, 90 soil samples were collected with metal cylinders (height 0.05 m, diameter 0.05 m) from the center of the layers 0-0.10; 0.10-0.20; 0.20-0.30 m. These samples were used to obtain the water retention curve, the penetration resistance curve and the soil bulk density (Bd), from which the LLWR and the critical bulk density (Bdc) were calculated. The critical limits of -80 hPa for field capacity (qfc), -15,000 hPa for wilting point (qwp), 2.5 MPa for soil resistance to penetration (qsr) and 0.10 m3 m-3 for air filled porosity (qafp) were used. The LLWR was highest in 0-0.10 m and qsr was the most relevant variable to reduce LLWR in all layers, especially the layers 0.10-0.20 m and 0.20-0.30 m. The Bdc decreased with depth for values of 1.68, 1.65 and 1.64 Mg m-3, respectively, in the layers 0-0.10, 0.10-0.20 and 0.20-0.30 m. The management of this soil under integrated crop livestock at a grazing height of 0.10 m had the highest frequency of soil samples with Bd≥Bdc.

de Carvalho K.,Instituto Agronomico Do Parana
Molecular genetics and genomics : MGG | Year: 2014

Polyploid plants can exhibit transcriptional modulation in homeologous genes in response to abiotic stresses. Coffea arabica, an allotetraploid, accounts for 75% of the world's coffee production. Extreme temperatures, salinity and drought limit crop productivity, which includes coffee plants. Mannitol is known to be involved in abiotic stress tolerance in higher plants. This study aimed to investigate the transcriptional responses of genes involved in mannitol biosynthesis and catabolism in C. arabica leaves under water deficit, salt stress and high temperature. Mannitol concentration was significantly increased in leaves of plants under drought and salinity, but reduced by heat stress. Fructose content followed the level of mannitol only in heat-stressed plants, suggesting the partitioning of the former into other metabolites during drought and salt stress conditions. Transcripts of the key enzymes involved in mannitol biosynthesis, CaM6PR, CaPMI and CaMTD, were modulated in distinct ways depending on the abiotic stress. Our data suggest that changes in mannitol accumulation during drought and salt stress in leaves of C. arabica are due, at least in part, to the increased expression of the key genes involved in mannitol biosynthesis. In addition, the homeologs of the Coffea canephora subgenome did not present the same pattern of overall transcriptional response, indicating differential regulation of these genes by the same stimulus. In this way, this study adds new information on the differential expression of C. arabica homeologous genes under adverse environmental conditions showing that abiotic stresses can influence the homeologous gene regulation pattern, in this case, mainly on those involved in mannitol pathway.

The objective of this work was to evaluate the effect of grazing height of palisade grass (Urochloa brizantha) on total organic carbon and on the physical quality of a Haplorthox (Rhodic Ferralsol), after soybean cropping and grazing periods on palisade grass, in a integrated crop-livestock system (ICL). A randomized complete block design with four treatments (grazing heights at 0.10, 0.20, 0.30, and 0.40 m) and three replicates was used, in the fourth and fifth years after the implementation of the ICL. Soil samples, taken from the 0-0.10 and 0.10-0.20-m soil depths, had sandy texture: 126 and 132 g kg-1 clay, respectively. The following variables were evaluated: total organic carbon, soil bulk density (Db), least-limiting water range (LLWR), and critical soil bulk density (Dbc). The physical quality of soil in the ICL system depends on the grazing height management on palisade grass in the autumn-winter period. Grazing height at 0.27 m provided the greatest values of total organic carbon and wider LLWR at 0.10-0.20-m soil depths. Palisade grass cultivation decreases more the frequency of soil samples with Db>Dbc than soybean cropping, and grazing height of palisade grass contributes to the improvement of soil physical quality.

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